The Wondrous Praying Mantis! Closest insect relative to the Roach NEW! I am currently in the process of raising a large number of praying mantises. I bought a 4600 cubic inch terrarium (roughly 12 x 12 x 20 ) and have filled it with plants. I have even provided an interesting environment: a 4 black African millipede and a 3 Madagascar hissing roach and a 20 green snake. The green snake will be ...